Automated loading/unloading of devices for burn-in testing

ABSTRACT

The automatic loading and unloading of devices for burn-in testing is facilitated by loading burn-in boards in a magazine with the stacked boards in the magazine moved into and out of a burn-in oven by means of a trolley. The trolley can include an elevator whereby a plurality of magazines can be stacked in the oven for the simultaneous burn-in testing of devices mounted on the burn-in boards. Each board has rollers on one end which are engagable by pneumatically actuated cam mechanisms for inserting the board into an electrical contact in the oven for burn-in tests. Preferably, the cam mechanisms allow for extraction of a single board for inspection.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 from U.S.Provisional Patent Application No. 60/766,316, filed Jan. 10, 2006,entitled “AUTOMATED LOADING/UNLOADING OF DEVICES FOR BURN-IN TESTING”;which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

This invention relates generally to the fabrication of semiconductordevices, and more particularly the invention relates to the loading andunloading of cycler boards into an oven for burn-in testing.

Literally millions of semiconductor devices are fabricated each year. Afinal step in the fabrication is a burn-in test of each packaged deviceto identify defective devices.

In carrying out the burn-in tests, a plurality of multi-layer printedcircuit boards or “burn-in” boards are provided with each board having aplurality of test sockets for receiving packaged devices for testing.One end of each board has contacts for mating with connectors of thetest apparatus to facilitate the testing of each device. One such testapparatus is the AEHR Corporation MTX oven which receives a plurality ofstacked boards for burn-in testing of devices in a heated environment.

Heretofore, packaged devices had been loaded automatically into aburn-in board at a Loader/Unloader Station with a human operatorsequentially providing the burn-in boards for device insertion into thetest sockets. After a full stack of burn-in boards have been loaded withpackaged devices, the human operator physically and sequentially moveseach board to the AEHR burn-in oven for testing. The process is timeconsuming and the placement of the loaded burn-in boards can bephysically taxing. Other burn-in systems employ a magazine for holding aplurality of burn-in boards which can be loaded into an oven in oneoperation. However, known systems employ a board latching mechanism atthe back of the oven for engaging board contacts with oven connectors.The mechanism is manually actuated, and the location at the back of theoven complicates routine maintenance of the mechanism.

The present invention is directed to alleviating these difficultiesfound in prior art burn-in systems.

SUMMARY OF THE INVENTION

In accordance with the invention, a magazine or carrier is provided fora plurality of stacked burn-in boards, and a trolley is employed to movethe magazine from the Loader/Unloader Station to the burn-in oven fortesting and for returning tested devices on the burn-in boards back toLoader/Unloader Station.

In one embodiment, the magazine has a plurality of rails for slidablyreceiving the burn-in boards with the top of the magazine being open toallow the insertion and removal of devices in the board sockets at theLoader/Unloader Station. The magazine has a bottom support surface whichcan move over rollers in the Loader/Unloader Station and in the oven tofacilitate movement into and out of the Loader/Unloader Station and theoven.

The trolley or cart is provided for moving a loaded magazine between theLoader/Unloader Station and the oven. The trolley has wheels tofacilitate the movement, and a support surface of the trolley hasrollers for receiving the bottom support surface of the magazine as aloaded magazine is moved into or out of the oven or the Loader/UnloaderStation.

In one embodiment, the trolley has an elevator for raising and loweringthe support surface of the trolley whereby a plurality of loadedmagazines can be stacked in the oven and in the Loader/Unloader Station.The trolley has alignment mechanisms such as rollers for physicallyengaging alignment members of the oven and the Loader/Unloader Stationin horizontal alignment. Optical sensors are employed for verticalalignment of the magazines, using the trolley elevator, in the oven andLoader/Unloader Station.

In accordance with an important feature of the invention, a loadedmagazine is moved to a position inside the oven with the board contactsabutting electrical connectors in the oven but not engaging theconnectors. A door of the oven, when closed, has mechanisms forinserting the burn-in board contacts into the oven connectors and forextracting the contacts from the connectors. Preferably, all boards canbe inserted together or separately. In one embodiment, each board hascam follower rollers at one end opposite from the contacts, and therollers engage cam surfaces of the pneumatically actuated mechanism.When actuated, the cam surfaces engage the rollers and slidably move oneor more boards in the magazine to engage the contacts or remove thecontacts from the connectors.

The invention and object and features thereof will be more readilyapparent from the following detailed description and appended claimswhen taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a burn-in board including cam-engagingrollers in accordance with one embodiment of the invention.

FIG. 2 is a perspective view of a burn-in oven as used in one embodimentof the invention.

FIG. 3 is a perspective view of a Loader/Unloader Station as used in oneembodiment of the invention.

FIG. 4 is a perspective view of a magazine for supporting a plurality ofburn-in boards.

FIG. 5 is a perspective view of a trolley for use in transportingmagazines.

FIG. 6 is a top view illustrating a trolley receiving or unloading amagazine at a Loader/Unloader Station.

FIGS. 7 a, 7 b are a top view and side view of a trolley loading orunloading magazines in a burn-in oven.

FIGS. 8 a, 8 b are plan views of a burn-in board in an oven withcontacts of the board abutting an oven connector and with contactsinserted into the connector, respectively, and further illustratingpneumatically actuated mechanisms in the oven door for inserting theburn-in board contacts into oven connectors and for extracting thecontacts from the connectors, respectively, in accordance with anembodiment of the invention.

FIG. 9 is a schematic of a controller for the pneumatically actuatedmechanism.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a perspective view of a burn-in board 10 which comprises amulti-layer printed circuit board. Mounted on one surface of board 10and connected with the multi-layer conductive layers of the printedcircuit board are sockets 12 which receive packaged integrated circuitdevices 14 for burn-in testing. At one end of board 10 are conductors 16which mate with connectors of a burn-in test apparatus for applyingelectrical signals to a device undergoing test. At an opposite end ofboard 10 are rollers 18 which as will be described are engaged by camsurfaces for the insertion and retraction of conductors 16 in and fromconnectors of the burn-in apparatus.

FIG. 2 is a perspective view of a conventional burn-in oven such as theAEHR MTX oven which has been modified to receive a burn-in boardmagazine assembly in accordance with the invention. Oven 20 includes anouter door 22 which provides a heat seal during burn-in testing and aninner door 24 which inserts and retracts burn-in boards in the ovenboard contacts or with conductors engaging connectors during the test. Alower support surface 26 and an upper support surface 28 are providedfor each receiving a magazine loaded with burn-in boards whereby themagazines can be stacked in the oven during test. Lower support surface26 has rollers 27 and upper support surface 28 has rollers 29 forengaging the magazine assembly during loading and unloading of themagazines in the oven. Guides 30 protrude from the base of oven 20 andfacilitate the horizontal alignment of a magazine with the oven forloading and unloading magazines.

FIG. 3 is a perspective view of a conventional board loader/unloaderelevator station 40 which withdraws boards from a magazine for theautomatic insertion and retraction of devices into burn-in boards inpreparation for burn-in testing or for final unloading and packaging ofacceptable devices. Station 40 includes a top support frame 42 includingrollers 44 for receiving a magazine and a bottom support frame 46including rollers 48 for receiving a magazine in a stacked arrangement.Guides 50 protrude from the loader/unloader station and providehorizontal alignment for a trolley when receiving or unloading magazinesat the loader/unloader station.

FIG. 4 is a perspective view of a magazine 60 for supporting a pluralityof burn-in boards in a stacked array. Magazine 60 includes a pluralityof vertical support frames 62 to which are mounted board support guides64 with opposing guides 64 slidably receiving burn-in boards in astacked array. Rails 67, 68 on the bottom surface 66 supports themagazine when placed in the loader/unloader station or in the burn-inoven. Rails 68 on the bottom are received in an alignment guide on atrolley when loading the magazine from the oven or the loader/unloaderstation to the trolley for transport. In operation, unloaded burn-inboards are sequentially removed from magazine 60 when in theloader/unloader station for the automatic insertion of packaged devicesinto sockets of the board and automatic extraction of devices from theboards.

FIG. 5 is a perspective view of a trolley for transporting burn-inboards in the magazine 60 of FIG. 4 to and from the burn-in oven of FIG.2 and the loader/unloader station of FIG. 3. Trolley 70 includes ahandle 72 for physically moving the trolley on rollers 74 between theoven and the loader/unloader station with a motor in housing 76actuating an elevator 78 for raising and lowering the top surface forthe receiving and dispensing of the stacked magazines. The top surfaceof the elevator includes a guide 80 for receiving rails 68 of themagazine with guide 80 having a stop portion for limiting the travel ofthe magazine when loaded on the elevator. Rollers 82 receive rails 68 ofthe magazine. An optical sensor 84 is used for vertical alignment of theelevator with the oven and the loader/unloader station, and roller guide86 mates with physical guides 50 of the loader/unloader station andguides 30 of the oven for horizontal alignment of the trolley whenloading and unloading magazines.

FIG. 6 illustrates trolley 70 positioned for receiving a loaded magazine60 at the loader/unloader station 40. Roller guides 86 of trolley 70align with guides 50 of the loader/unloader station for horizontalalignment, vertical alignment is effected by optical sensor 84 of themagazine and laser 52 of the loader/unloader station (FIG. 3) and laser32 of the oven (FIG. 2).

After a magazines is stacked on trolley 70 at the loader/unloaderstation, the trolley is physically moved to the oven as shown in FIG. 7a with roller guide 30 of the oven engaging roller 86 of the trolley forhorizontal alignment. FIG. 7 b is a side view illustrating the stackingof a magazine 60 on the upper shelf of oven 20. Elevator 78 raisesmagazine 60 until alignment sensor 84 of the trolley and alignmentsensor 32 of the oven indicate vertical alignment. Thereupon magazine 60is pushed into the oven and the trolley is removed.

Magazine 60 moves on rollers 29 on top shelf 28 of oven 32 (FIG. 2)until the magazine reaches a physical stop. At this position, theconnectors 16 of the burn-in boards are abutting connectors in the oven,but are not inserted therein, as illustrated in FIG. 8 a. Here thecontacts 16 of board 10 are abutting connector 90, but not insertedtherein. Inner door 24 of the oven is then closed with cam surfaces ofpneumatic actuated locking devices, for example, shown generally at 92engaging the rollers. Upon actuation of the pneumatically actuateddevices 92, the cam surfaces urge board 10 through rollers 18 forwardwith the contacts 16 engaging connector 90, as shown in FIG. 8 b.

The pneumatic actuators 92 on door 24 are further illustrated in FIGS. 8a, 8 b. In FIG. 8 a, rollers 18 of board 10 engage cam surfaces 94 ofthe pneumatic actuators 92. Upon actuation of pneumatic cylinders 96,the cam surfaces push rollers 18 and the burn-in board 10 as indicatedin FIG. 8 b, whereupon the contacts of board 10 engage connector 90. Theboard contacts are removed from the connector by reverse operation ofthe pneumatic actuator with cam surface 98 forcing rollers 18 to travelalong the cam surface 94 and back to the position in FIG. 8 a. After theinsertion of a magazine in the oven, all boards can be simultaneouslymoved with contacts engaging connectors or each individual board can bemoved by control of the pneumatic actuators for each board.

FIG. 9 is a schematic of a controller for the pneumatically actuatedboard insertion/retraction mechanism. A touch panel PLC 100 selects theboard for insertion or retraction. Panel 100 can be a conventional andcommercially available programmable logic controller such as the ProFace™ touch screen controller. A plurality of control lines extend fromthe panel to control pneumatic valves and air cylinders in theinsertion/extraction mechanism. For example, line 102 controls valve 104which connects a pressure line 106 to line 108 for inserting Board No. 1into a connector, or which connects line 106 to line 110 for extractingBoard No. 1 from the connector. Air cylinder 112 drives cam 114, and aircylinder 116 drives cam 118 in slidably moving board No. 1 for connectorinsertion or extraction.

The invention facilitates the transfer of burn-in boards fromloading/unloading stations to and from a burn-in oven with reducedphysical intervention of the human operator. While the invention hasbeen described with reference to specific embodiments, the descriptionis illustrative of the invention and is not to be construed as limitingthe invention. For example, actuators other than pneumatic can beemployed in the oven door for board insertion and retraction. Variousmodifications and applications may occur to those skilled in the artwithout departing from the spirit and scope of the invention as definedby the appended claims.

1. A method of transporting semiconductor devices on burn-in boardsbetween a board Load/Unload Station and an oven for burn-in testscomprising the steps of: a) providing a carrier for supporting aplurality of boards in a stacked array, b) stacking boards in thecarrier at the Load/Unload Station with semiconductor devicessequentially loaded into each board, c) transporting the carrier andboards to the burn-in oven, d) placing the carrier and boards into theoven with electrical contacts on each board abutting electricalconnectors of the burn-in oven, and e) sliding the boards and contactsinto engagement with the connectors for the performance of burn-in testson the semiconductor devices with a mechanism in a door of the ovenwhich engages the boards and slides the board contacts into engagementwith the connectors.
 2. The method of claim 1 wherein each boardincludes a plurality of rollers at one end of the board opposite fromthe electrical contacts at another end of the board, the mechanismincluding cam surfaces which receive the plurality of rollers and drivethe boards through the rollers when the cam surfaces are slid on therollers by pneumatic actuation.
 3. The method of claim 1 wherein themechanism is pneumatically actuated.
 4. The method of claim 2 whereinstep c) includes use of a trolley which abuts the Load/Unload Stationfor receiving a carrier with stacked boards and abuts the oven forplacing the carrier and boards into the oven in step d).
 5. The methodof claim 4 wherein the trolley, the oven, and the Load/Unload Stationhave rollers to facilitate the movement of a carrier with stacked boardsto and from the carrier.
 6. The method of claim 5 wherein in step d) thetrolley has an elevator for placing a plurality of carriers in a stackin the Load/Unload Station and in the oven.
 7. The method of claim 6 andincluding the step of horizontal alignment of the carrier with the ovenand with Load/Unload Station by a physical alignment mechanism of thetrolley and vertically aligning the carrier with the oven and theLoad/Unload Station by an optical alignment mechanism in the carrier. 8.The method of claim 1 wherein step c) includes use of a trolley whichabuts the Load/Unload Station for receiving a carrier with stackedboards and abuts the oven for placing the carrier and boards into theoven in step d).
 9. The method of claim 8 wherein the trolley, the oven,and the Load/Unload Station have rollers to facilitate the movement of acarrier with stacked boards to and from the carrier.
 10. The method ofclaim 9 wherein in step d) the trolley has an elevator for placing aplurality of carriers in a stack in the Load/Unload Station.
 11. Themethod of claim 1 wherein the mechanism allows for retraction of asingle board for inspection.
 12. Apparatus for burn-in testing ofpackaged semiconductor devices comprising: a) a carrier for supporting aplurality of boards and semiconductor devices mounted thereon in astacked array, b) a Load/Unload Station for inserting packagedsemiconductor devices sequentially into boards placed in the carrier, c)an oven for receiving a carrier with stacked boards and performingburn-in tests, the oven including electrical connectors for engagingboards for electrical testing, and a mechanism for engaging the boardsand sliding the boards into engagement with connector of the oven, andd) a trolley for abutting the Load/Unload Station and receiving acarrier with stacked boards and abutting the oven for delivering thecarrier and stacked boards.
 13. Apparatus of claim 12 wherein themechanism is pneumatically actuated.
 14. Apparatus of claim 12 whereinthe trolley, the oven, and the Load/Unload Station have rollers tofacilitate the movement of a carrier with stacked boards to and from thecarrier.
 15. Apparatus of claim 14 wherein in step d) the trolley has anelevator for placing a plurality of carriers in a stack in theLoad/Unload Station and in the oven.
 16. Apparatus of claim 15 whereinthe trolley includes a physical alignment mechanism for horizontalalignment of the carrier with the oven and with Load/Unload Station, andthe carrier includes an optical alignment mechanism for verticallyaligning the carrier with the oven and the Load/Unload Station. 17.Apparatus of claim 16 wherein the oven includes a door including thepneumatically actuated mechanism which when closed engages and slidesboards and contacts on one end of the boards into engagement with theelectrical connectors in the oven.
 18. Apparatus of claim 14 whereineach board includes a plurality of rollers at one end of the boardopposite from the electrical contacts at another end of the board, themechanism including cam surfaces which receive the plurality of rollersand drive the boards through the rollers when the cam surfaces are slidon the rollers by pneumatic actuation.
 19. Apparatus of claim 12 whereinthe trolley has an elevator for placing a plurality of carriers in astack in the oven.
 20. Apparatus of claim 19 wherein the trolleyincludes a physical alignment mechanism for use in horizontally aligningthe trolley a Load/Unload Station and an oven, and the carrier includesan optical alignment mechanism for use in vertically aligning thecarrier with oven and the Load/Unload Station.
 21. An oven for use inburn-in testing of electronic devices mounted on a burn-in boardscomprising: a) an oven chamber for receiving a plurality of stackedburn-in boards. b) a plurality of electrical connectors in the oven forreceiving contacts on the plurality of burn-in boards, and c) boardinsertion/retraction mechanisms for sliding boards into electricalcontact with the connectors and for removing the boards from electricalcontact with the connectors, and d) a door on the oven on which aremounted with board insertion/retraction mechanisms.
 22. The oven asdefined by claim 21 wherein each insertion/retraction mechanismcomprises at least one cam surface and a pneumatic cylinder for movingthe cam surface for inserting or retracting a board.
 23. The oven asdefined by claim 22 wherein each cam surface drives a cam followerattached to a board.
 24. The oven as defined by claim 23 wherein the camfollower comprises a roller attached to one end of a board opposite froman end having electrical contacts.
 25. The oven as defined by claim 23wherein each insertion/retraction mechanism includes two cam surfaces.26. The oven as defined by claim 21 wherein the boardinsertion/retraction mechanisms allow for extracting a single board forinspection.
 27. For use in a burn-in oven for sliding contact of aburn-in board into electrical contact with an electrical connector inthe oven, a board insertion/retraction mechanism comprising: a) at leastone cam surface for engaging a cam follower on a burn-in board, and b)an actuator for moving the cam surface and the burn-in board in theoven.
 28. The board insertion/retraction mechanism as defined by claim27 wherein the cam follower comprises a roller. 29 The boardinsertion/retraction mechanism as defined by claim 27 herein themechanism include two cam surfaces for engaging two rollers on a board.30. The board insertion/retraction mechanism as defined by claim 27wherein the actuator allows for extracting a single board forinspection.
 31. The board insertion/retraction mechanism as defined byclaim 27 wherein the actuator is pneumatically actual.